/* Dark Theme Color Variables */
:root {
    --primary-color: #4361ee;
    --secondary-color: #3a0ca3;
    --accent-color: #4cc9f0;
    --dark-color: #121212;
    --darker-color: #0a0a0a;
    --light-color: #1e1e1e;
    --text-color: #f8f9fa;
    --text-secondary: #adb5bd;
    --gray-color: #6c757d;
    --light-gray: #2a2a2a;
    --font-primary: 'Inter', sans-serif;
    --font-heading: 'Playfair Display', serif;
    --transition: all 0.3s ease;
    --shadow: 0 5px 15px rgba(0, 0, 0, 0.4);
    --border-radius: 8px;
}

/* Base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--dark-color);
    overflow-x: hidden;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

a {
    text-decoration: none;
    color: var(--primary-color);
    transition: var(--transition);
}

a:hover {
    color: var(--accent-color);
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 1rem;
    color: var(--text-color);
}

h1 {
    font-size: 3.5rem;
}

h2 {
    font-size: 2.5rem;
}

h3 {
    font-size: 1.75rem;
}

p {
    margin-bottom: 1.5rem;
    color: var(--text-secondary);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* Button styles */
.btn {
    display: inline-block;
    padding: 0.8rem 1.8rem;
    border-radius: var(--border-radius);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
}

.btn-sm {
    padding: 0.5rem 1.2rem;
    font-size: 0.9rem;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
    border: 2px solid var(--primary-color);
}

.btn-primary:hover {
    background-color: var(--secondary-color);
    border-color: var(--secondary-color);
    color: white;
}

.btn-secondary {
    background-color: var(--secondary-color);
    color: white;
    border: 2px solid var(--secondary-color);
}

.btn-secondary:hover {
    background-color: transparent;
    color: var(--secondary-color);
}

.btn-outline {
    background-color: transparent;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
}

.btn-outline:hover {
    background-color: var(--primary-color);
    color: var(--dark-color);
}

/* Section styles */
section {
    padding: 5rem 0;
    background-color: var(--dark-color);
}

.section-title {
    text-align: center;
    margin-bottom: 3rem;
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background-color: rgba(18, 18, 18, 0.95);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
    padding: 1rem 0;
    transition: var(--transition);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-family: var(--font-heading);
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text-color);
}

.logo:hover {
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    gap: 1.5rem;
    list-style: none;
}

.nav-links a {
    color: var(--text-color);
    font-weight: 500;
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: var(--transition);
}

.nav-links a:hover::after,
.nav-links a.active::after {
    width: 100%;
}

.menu-icon {
    display: none;
    cursor: pointer;
}

.bar {
    width: 25px;
    height: 3px;
    background-color: var(--text-color);
    margin: 5px 0;
    transition: var(--transition);
}

/* Hero section with Yonsei image */
.hero-section {
    height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero-bg-img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: url('../../images/campus_pic.jpg');
    background-size: cover;
    background-position: center;
    opacity: 0.7;
    z-index: -1;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    z-index: 1;
    background-color: rgba(0, 0, 0, 0.5);
    padding: 2rem;
    border-radius: var(--border-radius);
}

.hero-content h1 {
    margin-bottom: 1.5rem;
}

.hero-content p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 2rem;
}

/* About section */
.about-section {
    background: linear-gradient(to bottom, var(--dark-color), var(--light-color));
    position: relative;
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 3rem;
    align-items: center;
}

.about-img {
    position: relative;
    border-radius: var(--border-radius);
    overflow: hidden;
}

.about-img img {
    border-radius: var(--border-radius);
    width: 100%;
}

.about-text h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.skills {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin: 1.5rem 0;
}

.skill-tag {
    padding: 0.4rem 1rem;
    background-color: var(--light-gray);
    border-radius: 30px;
    font-size: 0.9rem;
    transition: var(--transition);
}

.skill-tag:hover {
    background-color: var(--primary-color);
    color: var(--dark-color);
    transform: translateY(-3px);
}

/* Research section */
.research-section {
    background-color: var(--light-color);
    position: relative;
}

.research-intro {
    text-align: center;
    max-width: 800px;
    margin: 0 auto 3rem;
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
}

.research-card {
    height: 300px;
    perspective: 1000px;
}

.card-inner {
    position: relative;
    width: 100%;
    height: 100%;
    text-align: center;
    transition: transform 0.8s;
    transform-style: preserve-3d;
}

.research-card:hover .card-inner {
    transform: rotateY(180deg);
}

.card-front, .card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    border-radius: var(--border-radius);
    padding: 2rem;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.card-front {
    background-color: var(--light-color);
    border: 1px solid var(--light-gray);
}

.card-back {
    background-color: var(--primary-color);
    color: white;
    transform: rotateY(180deg);
}

.card-back ul {
    text-align: left;
    margin-left: 1.5rem;
}

.card-back li {
    margin-bottom: 0.5rem;
}

/* Publications section */
.publications-section {
    background: linear-gradient(to bottom, var(--light-color), var(--dark-color));
    position: relative;
    padding: 5rem 0;
}

.publication-list {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

.publication-item {
    display: flex;
    margin-bottom: 2rem;
    background-color: var(--light-color);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease;
}

.publication-item:hover {
    transform: translateY(-5px);
}

.publication-year {
    background-color: var(--primary-color);
    color: white;
    font-weight: bold;
    padding: 1.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 80px;
}

.publication-content {
    padding: 1.5rem;
    flex: 1;
}

.publication-title {
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.publication-authors {
    color: var(--primary-color);
    margin-bottom: 0.3rem;
    font-style: italic;
}

.publication-venue {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.publication-links {
    display: flex;
    gap: 0.5rem;
}

.publication-link {
    padding: 0.3rem 1rem;
    background-color: var(--light-gray);
    color: var(--text-color);
    border-radius: 20px;
    font-size: 0.9rem;
    transition: var(--transition);
}

.publication-link:hover {
    background-color: var(--primary-color);
    color: white;
}

/* Contact section */
.contact-section {
    background-color: var(--dark-color);
    position: relative;
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
}

.contact-info {
    color: var(--text-color);
}

.contact-item {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
}

.contact-item i {
    font-size: 1.5rem;
    color: var(--primary-color);
}

.social-icons {
    display: flex;
    gap: 1.5rem;
    margin-top: 2rem;
}

.icon-3d {
    width: 40px;
    height: 40px;
    background-color: var(--light-gray);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-color);
    font-size: 1.2rem;
    transition: var(--transition);
}

.icon-3d:hover {
    background-color: var(--primary-color);
    color: white;
    transform: translateY(-5px) rotateY(20deg);
}

.contact-form {
    background-color: var(--light-color);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow);
}

.form-group {
    position: relative;
    margin-bottom: 1.5rem;
}

.form-control {
    width: 100%;
    padding: 1rem;
    background-color: var(--light-gray);
    border: 1px solid var(--gray-color);
    border-radius: var(--border-radius);
    color: var(--text-color);
    font-family: var(--font-primary);
}

.form-group label {
    position: absolute;
    top: 1rem;
    left: 1rem;
    color: var(--text-secondary);
    transition: var(--transition);
    pointer-events: none;
}

.form-group.focused label {
    transform: translateY(-20px);
    font-size: 0.8rem;
    color: var(--primary-color);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
}

textarea.form-control {
    height: 150px;
    resize: none;
}

/* Back to top button */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: var(--primary-color);
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    z-index: 999;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
}

.back-to-top.active {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background-color: var(--secondary-color);
    transform: translateY(-5px);
}

/* Animations and effects */
/* Particles Background */
#particles-js {
    position: fixed;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    z-index: -1;
    background-color: var(--dark-color);
}

/* Text Glitch Effect - Toned down */
.text-glitch {
    position: relative;
    display: inline-block;
    color: var(--text-color);
}

.text-glitch::before,
.text-glitch::after {
    display: none;
}

/* Text Scramble Effect */
.text-scramble {
    display: inline-block;
    color: var(--primary-color);
}

/* Scroll Down Animation */
.scroll-down {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    z-index: 10;
}

.mouse {
    width: 30px;
    height: 50px;
    border: 2px solid var(--primary-color);
    border-radius: 20px;
    position: relative;
    margin-bottom: 10px;
}

.wheel {
    width: 6px;
    height: 10px;
    background-color: var(--primary-color);
    border-radius: 3px;
    position: absolute;
    top: 10px;
    left: 50%;
    transform: translateX(-50%);
    animation: scroll-wheel 2s infinite;
}

@keyframes scroll-wheel {
    0% {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
    }
    100% {
        opacity: 0;
        transform: translateX(-50%) translateY(15px);
    }
}

.arrows {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.arrow-down {
    display: block;
    width: 12px;
    height: 12px;
    border-right: 2px solid var(--primary-color);
    border-bottom: 2px solid var(--primary-color);
    transform: rotate(45deg);
    margin: -3px 0;
    animation: arrow-scroll 2s infinite;
}

.arrow-down:nth-child(2) {
    animation-delay: 0.2s;
}

@keyframes arrow-scroll {
    0% {
        opacity: 0;
        transform: rotate(45deg) translate(-5px, -5px);
    }
    50% {
        opacity: 1;
    }
    100% {
        opacity: 0;
        transform: rotate(45deg) translate(5px, 5px);
    }
}

/* Floating Shapes */
.floating-shapes {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    z-index: -1;
    overflow: hidden;
    pointer-events: none;
}

.shape {
    position: absolute;
    border-radius: 50%;
    animation: float 10s ease-in-out infinite;
}

.shape-1 {
    width: 80px;
    height: 80px;
    background: linear-gradient(45deg, var(--primary-color), transparent);
    top: 20%;
    left: 10%;
    animation-delay: 0s;
}

.shape-2 {
    width: 60px;
    height: 60px;
    background: linear-gradient(45deg, var(--secondary-color), transparent);
    top: 60%;
    left: 80%;
    animation-delay: 2s;
}

.shape-3 {
    width: 40px;
    height: 40px;
    background: linear-gradient(45deg, var(--accent-color), transparent);
    top: 30%;
    left: 70%;
    animation-delay: 4s;
}

@keyframes float {
    0% {
        transform: translateY(0) rotate(0deg);
    }
    50% {
        transform: translateY(-20px) rotate(180deg);
    }
    100% {
        transform: translateY(0) rotate(360deg);
    }
}

/* Floating Bubbles */
.floating-bubbles {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    overflow: hidden;
    z-index: -1;
    pointer-events: none;
}

.bubble {
    position: absolute;
    border-radius: 50%;
    background: radial-gradient(circle at 30% 30%, rgba(255, 255, 255, 0.3), rgba(67, 97, 238, 0.2));
    box-shadow: 0 0 10px rgba(67, 97, 238, 0.2);
    animation: bubble-float 15s linear infinite;
}

@keyframes bubble-float {
    0% {
        transform: translateY(0) translateX(0) scale(1);
        opacity: 0;
    }
    10% {
        opacity: var(--bubble-opacity, 0.2);
    }
    100% {
        transform: translateY(-100vh) translateX(20px) scale(1.5);
        opacity: 0;
    }
}

/* Gradient Border */
.gradient-border {
    position: relative;
    border-radius: var(--border-radius);
    overflow: hidden;
}

.gradient-border:before {
    content: '';
    position: absolute;
    top: -2px;
    left: -2px;
    right: -2px;
    bottom: -2px;
    background: linear-gradient(45deg, 
        var(--primary-color), 
        var(--secondary-color), 
        var(--accent-color), 
        var(--primary-color));
    background-size: 400% 400%;
    z-index: -1;
    animation: gradient-animate 6s ease infinite;
    border-radius: calc(var(--border-radius) + 2px);
    opacity: 0.7;
}

@keyframes gradient-animate {
    0% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
    100% {
        background-position: 0% 50%;
    }
}

/* Neon text effect - toned down for dark theme */
.neon-text {
    color: var(--primary-color);
    text-shadow:
        0 0 5px var(--primary-color),
        0 0 10px var(--primary-color);
    animation: flicker 2s infinite alternate;
}

@keyframes flicker {
    0%, 19%, 21%, 23%, 25%, 54%, 56%, 100% {
        text-shadow:
            0 0 5px var(--primary-color),
            0 0 10px var(--primary-color);
    }
    20%, 24%, 55% {
        text-shadow: none;
    }
}

/* Rain effect */
.rain-container {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    overflow: hidden;
    pointer-events: none;
    z-index: -1;
}

.rain {
    position: absolute;
    width: 2px;
    height: 25px;
    background-color: rgba(67, 97, 238, 0.3);
    top: -25px;
    animation: rain-fall linear infinite;
}

@keyframes rain-fall {
    0% {
        top: -25px;
        opacity: 0;
    }
    5% {
        opacity: 0.5;
    }
    90% {
        opacity: 0.5;
    }
    100% {
        top: 100%;
        opacity: 0;
    }
}

/* Shiny button effect */
.shiny-btn {
    position: relative;
    overflow: hidden;
    z-index: 1;
}

.shiny-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(
        90deg,
        transparent,
        rgba(255, 255, 255, 0.3),
        transparent
    );
    transition: left 0.7s;
    z-index: -1;
}

.shiny-btn:hover::before {
    left: 100%;
}

/* Typing text animation */
.typing-text {
    display: inline-block;
    white-space: nowrap;
    overflow: hidden;
    border-right: 2px solid var(--primary-color);
    animation: 
        typing 3.5s steps(30, end),
        blink-caret .75s step-end infinite;
    color: var(--text-color);
}

@keyframes typing {
    from { width: 0 }
    to { width: 100% }
}

@keyframes blink-caret {
    from, to { border-color: transparent }
    50% { border-color: var(--primary-color) }
}

/* Electric border */
.electric-border {
    position: relative;
    border-radius: var(--border-radius);
    overflow: hidden;
}

.electric-border::before {
    content: '';
    position: absolute;
    top: -2px;
    left: -2px;
    right: -2px;
    bottom: -2px;
    z-index: -1;
    background: linear-gradient(
        90deg,
        var(--primary-color),
        var(--secondary-color),
        var(--accent-color),
        var(--primary-color)
    );
    background-size: 200% 200%;
    animation: border-rotate 3s linear infinite;
    border-radius: calc(var(--border-radius) + 2px);
}

@keyframes border-rotate {
    0% {
        background-position: 0% 50%;
    }
    100% {
        background-position: 200% 50%;
    }
}

/* Animated underline effect */
.animated-underline {
    position: relative;
    display: inline-block;
}

.animated-underline::after {
    content: '';
    position: absolute;
    width: 100%;
    transform: scaleX(0);
    height: 2px;
    bottom: -5px;
    left: 0;
    background-color: var(--primary-color);
    transform-origin: bottom right;
    transition: transform 0.4s cubic-bezier(0.86, 0, 0.07, 1);
}

.animated-underline:hover::after {
    transform: scaleX(1);
    transform-origin: bottom left;
}

/* Wave container */
.wave-container {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
}

.wave-container svg {
    display: block;
}

/* Preloader */
.preloader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--dark-color);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 9999;
    transition: opacity 0.5s ease;
}

.spinner {
    width: 60px;
    height: 60px;
    position: relative;
}

.double-bounce1, .double-bounce2 {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    background-color: var(--primary-color);
    opacity: 0.6;
    position: absolute;
    top: 0;
    left: 0;
    animation: bounce 2s infinite ease-in-out;
}

.double-bounce2 {
    animation-delay: -1.0s;
}

@keyframes bounce {
    0%, 100% {
        transform: scale(0);
    }
    50% {
        transform: scale(1);
    }
}

/* Text scramble dud effect */
.dud {
    color: var(--primary-color);
    opacity: 0.8;
}

/* Responsive styles */
@media (max-width: 1024px) {
    h1 {
        font-size: 3rem;
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .about-img {
        max-width: 400px;
        margin: 0 auto;
    }
}

@media (max-width: 768px) {
    h1 {
        font-size: 2.5rem;
    }
    
    .menu-icon {
        display: block;
    }
    
    .nav-links {
        position: fixed;
        top: 0;
        right: -100%;
        height: 100vh;
        width: 70%;
        background-color: var(--dark-color);
        flex-direction: column;
        align-items: center;
        padding-top: 5rem;
        transition: var(--transition);
        box-shadow: -5px 0 15px rgba(0, 0, 0, 0.3);
    }
    
    .nav-links.active {
        right: 0;
    }
    
    .contact-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 576px) {
    h1 {
        font-size: 2rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    section {
        padding: 3rem 0;
    }
    
    .research-grid {
        grid-template-columns: 1fr;
    }
    
    .publication-item {
        flex-direction: column;
    }
    
    .publication-year {
        width: 100%;
        padding: 0.8rem;
    }
}

/* Work Experience Timeline */
.experience-section {
    padding: 5rem 0;
    background-color: var(--dark-color);
}

.timeline {
    position: relative;
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 0;
}

.timeline::before {
    content: '';
    position: absolute;
    width: 2px;
    background-color: var(--primary-color);
    top: 0;
    bottom: 0;
    left: 50px;
    margin-left: -1px;
}

.timeline-item {
    padding: 0 0 2rem 80px;
    position: relative;
}

.timeline-dot {
    width: 20px;
    height: 20px;
    background-color: var(--primary-color);
    border-radius: 50%;
    position: absolute;
    left: 40px;
    top: 0;
    margin-left: -10px;
    z-index: 1;
}

.timeline-content {
    padding: 1.5rem;
    background-color: var(--light-color);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.timeline-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 1rem;
}

.timeline-title h3 {
    margin-bottom: 0.3rem;
    color: var(--text-color);
}

.timeline-title .company {
    font-size: 1rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.timeline-info {
    display: flex;
    flex-direction: column;
    text-align: right;
}

.timeline-date, .timeline-location {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.company-link {
    margin-top: 1rem;
}

.company-link a {
    display: inline-flex;
    align-items: center;
    font-size: 0.9rem;
    color: var(--primary-color);
    text-decoration: none;
    transition: var(--transition);
}

.company-link a i {
    margin-left: 0.5rem;
    font-size: 0.8rem;
}

.company-link a:hover {
    text-decoration: underline;
}

@media (max-width: 768px) {
    .timeline-header {
        flex-direction: column;
    }
    
    .timeline-info {
        text-align: left;
        margin-top: 0.5rem;
    }
}

.university-logo {
    margin-bottom: 1.5rem;
}

.university-logo img {
    height: 80px;
    width: auto;
    margin: 0 auto;
}